Philadelphia, PA: The enactment of statewide medicinal marijuana laws is associated with significantly lower state-level opioid overdose mortality rates, according to data published this week in the Journal of the American Medical Association (JAMA) Internal Medicine.

A team of investigators from the University of Pennsylvania, the Albert Einstein College of Medicine in New York City, and the Johns Hopkins Bloomberg School of Public Health in Baltimore conducted a time-series analysis of medical cannabis laws and state-level death certificate data in the United States from 1999 to 2010 - a period during which 13 states instituted laws allowing for cannabis therapy.

Researchers reported, "States with medical cannabis laws had a 24.8 percent lower mean annual opioid overdose mortality rate compared with states without medical cannabis laws." Specifically, overdose deaths from opioids decreased by an average of 20 percent one year after the law's implementation, 25 percent by two years, and up to 33 percent by years five and six.

In a written statement to Reuters Health, the study's lead author Dr. Marcus Bachhuber said: "Most of the discussion on medical marijuana has been about its effect on individuals in terms of reducing pain or other symptoms. The unique contribution of our study is the finding that medical marijuana laws and policies may have a broader impact on public health."

Added co-author Colleen L. Barry in USA Today: "[The study's findings] suggest the potential for many lives to be saved. ... We can speculate ... that people are completely switching or perhaps supplementing, which allows them to lower the dosage of their prescription opioid."

Nationwide, overdose deaths involving opioid analgesics have increased dramatically over the past decade. While fewer than 4,100 opiate-induced fatalities were reported for the year 1999, by 2010 this figure rose to over 16,600 according to an analysis by the US Centers for Disease Control.

According to a series of clinical trials overseen by the University of California, San Diego, the inhalation of whole-plant cannabis is safe and efficacious in the treatment of various types of neuropathy - a type of pain that is poorly managed by opiates. Moreover, clinical data published in 2011 in the journal Clinical Pharmacology & Therapeuticsreported that cannabis administration significantly augments the analgesic effects of opiates in patients with chronic pain.

A separate review published in the Harm Reduction Journal in 2012 concluded, "Prescribing cannabis in place of opioids for neuropathic pain may reduce the morbidity and mortality rates associated with prescription pain medications and may be an effective harm reduction strategy."